AUSTRALIANS booked to fly to Bali last night had their flights cancelled after ash from an erupting volcano was blown dangerously close to Denpasar airport.

Mount Bromo, a popular Indonesian tourist destination in East Java, has been erupting all week but last night airlines were forced to cancel flights to Bali when ash drifted towards its international airport.

Six Jetstar flights were cancelled. One flight from Perth to Denpasar which was already in the air was diverted to Darwin, and the rest were grounded.

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The airline was monitoring the situation and would advise passengers of any further delays, a spokeswoman said.

Customers whose flights were cancelled would be given the option of rescheduling for a time within the next three months, or accepting a full refund.

Virgin Blue flights to the area were also cancelled.

A spokeswoman said three or four flights were grounded last night and another two cancelled this morning.

"Virgin Blue would like to advise that, as a precautionary measure, all flights to and from Bali have been cancelled for the next 24-hours," the airline said in a statement at 8pm last night.

A meteorologist at the Darwin Volcanic Ash Advisory Centre, Billy Lynch, said the volcano could disrupt flights for several days.

"If it continues to erupt and the wind continues to blow the ash towards the airports, there could be disruptions," he said. "It won't really clear until the winds change … once there is ash in the atmosphere it tends to stay a while."

The eruption was moderate compared with Merapi volcano's eruption last year, which displaced 280,000 people and left 153 dead.

Mount Bromo is part of the Tengger Caldera, a collection of five volcanos in the Bromo-Tengger-Semeru National Park.